In the packaging of many liquid household products, e.g., window cleaners, insect poisons cleaning fluids, etc., it has been found market-attractive to include, as part of the package, a finger actuated dispensing pump. These pumps are generally fitted with nozzles which are capable of product delivery in a spray mode and/or a stream mode. Most nozzles produce the spray mode by causing the liquid product to be broken up into small particles as it is dispensed from the nozzle. This breaking up of the liquid is generally accomplished by forcing the liquid to traverse a swirling path as it exits the nozzle outlet orifice. The swirling path can be accomplished by the use of any of the well known "swirl chamber" devices which are associated with the nozzle. See for example the devices of U.S. Pat. Nos. 4,358,057; 4,257,751; and 4,161,288.
The spray mode of delivery is preferred over the stream mode in those applications where the product is to be applied evenly over a relatively large area. However, due to the break-up of the liquid, some of the product will be delivered as a fine mist. Also a fine mist can be formed when the product impacts the surface on which it is sprayed. When the product is applied in an enclosed area, e.g. a shower stall, there is the possibility that the user will inhale some of the mist. Even in open areas the mist is apt to settle where not desired, e.g. the users wearing apparel. When the product is toxic or corrosive this inhalation and settling is undersirable if not blatantly dangerous.
To overcome the problems created by the fine mist, the pump industry has tried aeration of the small liquid particles subsequent to their exiting the swirl chamber. Such aeration gives at least a portion of the dispensed liquid a foam characteristic which does not yield the unwanted fine mist--indeed the foamed liquid is further beneficient in that it entraps any fine mist which comes into contact with it. Aeration of the small liquid particles is conventionally achieved by providing an open ended chamber which surrounds and extends outwardly of the nozzle outlet orifice and which has aspirating ports generally located between the nozzle outlet orifice and the open end of the chamber. More specifically, it has heretofore been assumed that these aspiration ports should be located between the nozzle outlet orifice and the back-side of the cone shaped spray pattern. (The formation of the cone pattern is a well recognized characteristic of swirl chambers). While the use of the chamber with its aspiration ports does provide aeration by entrapment of aspirated air, this system is not without a major drawback. To obtain proper aeration the aspiration ports must remain open. However, due to the close proximity of the ports to the dispensed liquid, the ports may become at least partially filled with the dispensed liquid. Such liquid, when it dries, could lead to clogging of the ports. With the aspiration ports partially or completely clogged proper aeration can be compromised.
It is therefore an object of this invention to provide a nozzle which provides for aeration of a liquid product that is dispensed through a swirl chamber without the utilization of the above described aspiration ports.